Rod guide and paraffin scraping devices of the type illustrated and described in the U.S. Pat. No. 3,399,730 are necessarily made of substantially rigid substances to reduce their wear by contact with the internal surfaces of the well flow conductor, such as a tubing string, during the reciprocation in the tubing string of the pump rod string on which they are installed. Since the diameters of the rods vary to some degree or another, as much as plus or minus ten thousandths of an inch, such conventional rod devices are provided with means, such as the internal longitudinal ribs described in the U.S. Pat. No. 3,399,730, which are intended to "bite into or cut through any corrosion or coating which may be present on the outer periphery of the rod . . . " In actual practice such ribs often tend to collapse or bend, and in any case the longitudinal spaces therebetween provide constricted longitudinal flow passages between the rods and the internal surfaces of such rod devices. Flow of well fluids, which often contain abrasive particles such as sand suspended therein, through such passages results in abrasion and weakening of the rods at the locations of these devices. In addition, the collapse or bending of such ribs which may occur during pumping due to contact of the devices with the internal surfaces of the well tubing results in loosening of such devices on the rods and their movement relative thereto as they contact the internal surfaces of the well tubing. Since the devices when used as centralizers or scrapers must be spaced at predetermined intervals on the rods to operate effectively, their displacement from their initial installed positions may result in undesired lateral displacement of some sections of the pump rod string when the devices are used as rod centralizers or in failure of the devices to scrape some portions of the internal surfaces of the flow conductor and thus accumulation of deposits of paraffin on such unscraped portions may occur.
It is desirable therefore that pump rod string devices such as centralizers and/or scrapers be provided which have means for rigidly holding the devices on the rods, which do not permit flow of fluids between the devices and the rods which may be formed of very rigid wear resistant substances and which are easily installable on the rods of the pump rod string.
Accordingly, it is an object of this invention to provide a new and improved well tool which is easily and rigidly installable on a rod.
Another object is to provide a well tool having a pair of complementary longitudinally telescopical sections which are rigidly securable on a rod upon longitudinal telescopical movement of one section relative to the other into locked relationship about the rod.
Still another object is to provide a well tool, of the type described, having a compressible member interposed between one section and the rod for enabling the installation of the well tool on rods of varying diameters.
Still another object is to provide a well tool, of the type described, wherein the complementary sections are provided with co-engageable tongue and groove means for moving said sections toward one another to compress the resilient member against the rod upon telescopical movement of one section relative to the other into locked position on the rod.
Still another object is to provide a well, tool, of the type described, wherein the two sections have co-engageable lock means for locking the sections to one another when installed on a rod.
An important object of the invention is to provide a well tool, of the type decribed, wherein the well tool section compressing the resilient member has a plurality of grooves for receiving portions of the resilient member as the resultient member is compressed against the rod whereby the well tool may be installed on rods of different diameters.